Work holding clamp



N0 25, 1952 A. o. MATHISON WORK HOLDING CLAMP Filed sept, 15 195o Patented Nov. 25, 1952 UNITED STATES PATENT O FFI-'CE 'WORK-HOLDING CLAMP Albert'O. Mathison, Brookl'ynfNY.

Applcatiomselltenberl 1950, Sei'ilN 0. "181,969

3 Gla'ims. (Chim-'59) devices which are adapted to be utilized forhold- ",illg'work :pieces cn the -bed or work supporting "s'tati'n of a drill press, lathe, milling machine,

boring machine, planer, band saw, grinder and the likernachine tools.

Accordingly, an object of the present invention is to provide such a clamping device which 'is simple in construction and is 'readily'appliedand removed. 7

Another object i's -to provide such a device which holds the work pieces-on the machine bed in 'a manner to 'facilitate access thereto for 'per'- forr'riing a desired operation vwith the tool ofthe machine.

Another object is to provide' such a device which is adjustable and has self aligning elements, whereby its use is feasible in connection with work pieces of a large variety of sizes and shapes.

A further object is to provide such a device which is compact in construction and is sumciently rugged to withstand the rough usage to which'it may normally be subjected.

Other and further 'objects will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not 'referred to herein will occur to 'one skilled in the art upon employment of the invention in practice.

A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying 'drawings, fol-ming a-part of the specification, wherein:

Fig. 1 is a plan view of a clamping device in accordance with the invention, illustrating the same positioned to hold a work piece on the bed of a machine tool. v

-Fig. 2 is a sectional view taken along the line 2--2 on Fig. 1. v

Fig. 3 is an enlarged plan view illustrating the strap element of the device.

Fig. 4 is a fragmentary sectional view of the portion of the device shown in Fig. 2 at the right side thereof, illustrating a modified arrangement for linking a gripping member to the strap.

Fig. 5 is a fragmentary plan view, illustrating a modified arrangement for adjusting the device with respect to the work piece.

Fig. 6 is a side view of a portion of the device shown in Fig. 5, partly in section and partly in elevation.

Fig. 7 is a. sectional view taken along the line 1-1 on 5. i

Referring now to the drawing in'detail `and more particularly to Figs. l, 2, and. g3 thereof, there is shown a bed 'B of a machine tool -havihg' T-shaped grooves'G formed therein, and 4a work piece W held'on the -bed by 'a clampingdevice =t0 inraccordance with the invention.

Generally described, the device t0 comprises ian elongate strap l l, a ipair of-g'ripping members (2. linked to thestrap by .pins 14, -la bolt 'l5 having a head 'adapted 'to be disposed in =one of the grooves G, and a nut =I for -retaiing ail'eleme'nt l1 -on the -bolt which provides aipivotal 'connection between the bolt and the stra-pinlthe manner described hereinafter.

The lstrap is -a rigid plate 'like member ha'viiig apertures i9 4{"Fl'g.'3) extedingitlferethroughwith cne'apertureladj'acent each'end thereof. Each ''f the apertures has a counte'isunk -i1p`pe` portion providing a shoulder 20. 'a generally hemisptierical lower surface lirviding Faisocketl, and'fan intermediate downwardly 'and 'outwardly n'a'r'l portion 22 (Fig. 2). -'A longitudinally eic'teiidng slot 2-4 is formed in the strap between the einer tures 19, which slot, in this 'embodi'r'niit, has a generally hemispherical surface 25 at each end thereof adjacent the upper surface of the 'strap for reception 'of the element I1. Preferably, 'a's illustrated and for the 'purpose which will be'- COme apparent hereinafter, one end portion F01 the strap is offset vertically at 42li with r'espe'ctt'o the horizontal axis thereof.

The gripping members tifare generally liriiispherical in shape (Fig. l2)-. -Ea'ch member f2 has a substantially flat underside 'o'r gi'irng's'urface 21 and a generally 'heini-spherical' upper-'surface 29 providing a ball-like element for reception ln the socket formation 25|. aperture entends centrally through each gripping member' from the upper to the lower surface, and is 'formed with a. lower recess '30, afcdnstric'ted portion pfoviding a shoulder 31 :and fan upper, upwardly and outwardly aredptionZ.

nach of tlie plus r4 has a heed 3?4 attach 'ena thereof for respectively engaging the snot-aders 20 and 3| 'to link th ipping nienlbes the strap for universal movement. The lower head of the pin is the recess 1U and 4'the spank of the pin rs 'in the nared portions "z2 'mi lf2,y Athus facilitating rotative movement of the o grinning member about and transversely of the aXS 0f the pin. This afagement gripping members free floating andself-aligning with respect to the stralend 4'enz'ibles 'the device to hold work lpieces which have inclined upper surfaces on the "-bed.

It will of course be understood that the above ball joint could be provided by forming the strap with the ball elements and the gripping members with the socket formations, although the foregoing arrangement is preferred from a viewpoint of simplicity of manufacture.

The element I1 is substantially hemi-spherical in form, and has a central aperture 35 extending therethrough for reception of the bolt I5. The underside of this element has a generally hemispherical surface 3G adapted to be received by the surface 25 of the strap, whereby, as shown, the strap is pivotally connected with the bolt for universal movement and is self adjusting.

The surface 25 in which the element I'I is to be seated is selected by the operator depending upon the height or thickness of the work piece and the angle at which the strap member is most effective to hold the work piece. Also, as shown, if the work piece has considerable height or thickness, the member I2 at the oiset strap end is' utilized to engage the work piece and a shim S is placed under the gripping member at the other end of the strap, so that the angle at which the strap is inclined is not too extreme, the thickness of the compensating shim being selected in accordance with the height of the work. Similarly, a thin work-piece, such as a disc or plate may be engaged by the gripping member at the end of the strap opposite the offset end, and a compensating shim of a desired thickness may be placed under the gripping member at the offset end of the strap.

In Fig. 4, a modified arrangement is illustrated which 'facilitates universal movement between the upper head 34a of the pin and its supporting shoulder 2lla. To accomplish this, this head has a hemi-spherical surface and this shoulder has a corresponding hemispherical surface.

In Figs. 5, 6, and '1. a modified arrangement is shown which provides adjustment of the bolt lengthwise with respect to the strap. In this arrangement, the upper surface of the strap I I has a plurality of pairs of arcuate transversely aligned recesses 4U (three being shown, for example), a recess of each pair being located at one side of the slot 24. lThe element II' has a pair of diametrically opposite arms 4I formed with arcuate surfaces for cooperation with the recesses 40. The arms may be selectively positioned in a pair of recesses to pivotally connect the bolt I5 to the strap and to facilitate adjustment of the angle of the strap.

In use, the devices in accordance with any of the embodiments illustrated and described herein are positioned with respect to the bed B and the work piece W and the shim S (if required), for example, as shown in Fig. 2, and the nut I6 is threaded on the bolt I5 to cause the element I'I to bear downwardly cn the strap I I, whereby the work piece is securely held on the bed for performing the desired tool operation thereon. While the work piece is being so secured, the gripping members, the strap and the bolt are self aligned by reason of the universal or pivotal connections, whereby the flat underside 21 of the gripping members is in the plane of the surface of the work piece engaged by it and damage to the work piece is prevented by such engagement.i

From the foregoing description it will be seen 70 that the present invention provides novel and useful clamping devices of the character indicated herein which devices are extremely simple and economical in construction and are adapted for a wide variety of uses. The devices are readily applied and removed, and are practically indestructible.

From the foregoing it will be apparent that the device of this invention has many advantages over the prior art devices, as far as applicant is aware. To enumerate a few of these advantages, by the employment of applicants free floating device, it is no longer necessary that the top surface of the work piece be horizontal but may be at an angle in any direction, thereby saving labor. time, and the various sized shims required in shimming the work piece to a true horizontal level for the prior art clamp. A saving in time and labor also results particularly where the face plate is vertical. In this instance one hand is required for the wrench and the other hand for holding the device, so that it is necessary to have assistance of another person for holding the blocking or shim in place.

Another advantage resides in the use of a shorter bolt-with the instant device in view cf the slant or inclination at which applicant's strap may be placed. In addition, injury to the workman is substantially minimized by the projecting bolt of the prior art devices, which bolt end is generally well above the surface of the work:

clamp. In applicant's device the offset portion of the strap causes the end of the bolt to fall substantially even with the uppermost portionof the strap, as is evident from Fig. 2.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacricing any of its advantages, it is to be understood that all matters are to be interpreted as illustrative and not in any limiting sense.

What I claim is: Y

1. A clamping device comprising an elongate strap having an aperture extending therethrough adjacent each end thereof, said apertures each having a shoulderv at the upper end, a generally hemi-spherical surface at the lower end and al downwardly and outwardly flared intermediate portion; a pair of gripping members each having a generally ilat, lower surface, a generally hemispherical upper surface and an aperture extending from said upper surface to said lower surface, said last mentioned aperture having a constricted intermediate portion providing a shoulder and having an upwardly and outwardly flared upper portion; said members each having its hernispherical surface facing one of the hemi-spherical surfaces of said strap; and a pair of pins each extending through one of said strap apertures and one of said member apertures, said pins each having a head at each end thereof for engaging said shoulder portions.

2. A clamping device comprising an elongate strap having an aperture extending therethrough adjacent each end thereof, said apertures each having a shoulder at the upper end, a generally hemi-spherical surface at the lower end and a downwardly and outwardly flared intermediate portion; a pair of gripping members each having a generally nat, lower surface, a generally hemi-spherical upper surface and an aperture extending from said upper surface to said lower surface, said last mentioned aperture having a constricted intermediate portion providing a shoulder and having an upwardly and outwardly flared upper portion; said members each having its hemi-spherical surface facing one of the hemispherical surfaces of said strap; a pair of pins each extending through one of said strap apertures and one of said member apertures, said pins each having a head at each end thereof for engaging said shoulder portions; said strap having a longitudinal slot intermediate the apertures thereof and having a plurality of recesses adjacent the upper end thereof and said slot; a bolt extending through said slot; and a member on said bolt having a surface cooperating with said recesses to pivotally interconnect said bolt and strap. I

3. A device according to claim 2, wherein said recesses extend transversely with respect to said slot and complementary recesses are formed at each side of said slot having an arcuate surface, and said member on said bolt has a pair of arms each formed with an arcuate surface adapted to cooperate with an arcuate surface of one of said recesses.

ALBERT O. MATHISON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,676,289 Schmalz A July 10, 1928 2,325,387 Frederickson July 27, 1943 2,421,957 Mead June l0, 1947 FOREIGN PATENTS Number Country Date 549,078 Great Britain Nov. 5, 1942 570,518 Great Britain July 10, 1945 583,756 Great Britain Dec. 30, 1946 

